Search PubMed⌕ Search

Biomedical subjects

W M Britton

Publications and source records attributed to W M Britton.

35 records · Page 2Linked to original sources
PubMed1975

Influence of high levels of DDT in the diet on liver microsomal estrogen metabolism in the laying hen.

Two experiments were conducted with laying hens to evaluate the effect of technical grade DDT on estrogen metabolism by liver microsomes using an assay which measured the metabolism of estradiol-17beta-4-14C. In Experiment I feeding 500 ppm DDT in the diet had no significant effect on estrogen metabolism after 10 days. However, the metabolism was increased after 18 days and more than doubled after 51 days. In Experiment II hens were fed diets containing 0, 300, 600 or 1200 ppm DDT and estrogen metabolism by liver microsomes was examined at 0, 7, 14, 21 and 35 days. A significant increase in estrogen metabolism was seen at 14 days with the feeding of 600 or 1200 ppm DDT and at 21 days with 300 ppm DDT. The ability to metabolize estrogen reached a maximum increase of approximately two-fold in all hens fed DDT. This required 14 days when the birds were fed 1200 ppm DDT, 21 days when fed 600 ppm DDT and 35 days when fed 300 ppm DDT. The increase in estrogen metabolism caused by DDT was found to be dose and time dependent.

Analysis of Variance↗
PubMed1975

Toxicity of high dietary levels of DDT in laying hens.

White Leghorn hens were fed diets containing 0, 300, 600, or 1200 ppm technical grade DDT for three 28-day periods. The 1200 ppm diet caused tremors and 33% mortality in the final period, but no gross toxicity symptoms were seen in birds fed the other diets. Egg production was decreased during the third period by 600 or 1200 ppm. Egg weight was decreased during the third period by 600 or 1200 ppm. Egg weight was decreased during the last two periods by 1200 ppm. Shell thickness was decreased in all three periods by feeding 600 or 1200 ppm DDT. Dietary DDT caused no change that could be detected by shell beta backscatter. Shell weight as a percent of total egg weight was decreased by 600 or 1200 ppm DDT.

Analysis of Variance↗
PubMedDate not supplied

Pathology of experimental vitamin D deficiency in turkeys and the effects of various vitamin D supplements.

One-day-old poults fed a vitamin D3-deficient diet were examined for clinical, biochemical, and morphological changes at 14 days of age. Changes in these parameters were compared at 15.5 and 17 days of age after one of the following vitamin D-replacement therapies was provided: water-soluble vitamin-mineral packs that contained vitamin D3; vitamin D3 in the feed; or vitamin D, 1,25-dihydroxyvitamin D3 in the feed. The vitamin D3-deficient poults were lame and had significant decreases in weight gain and in longitudinal skeletal growth. None of the therapies alleviated all these changes, but clinical lameness subsided in poults provided 1,25-dihydroxyvitamin D3. Calcium concentrations were significantly improved by all therapies. Treatment with vitamin D3 in the feed and water significantly increased 25-hydroxyvitamin D3 concentrations in vitamin D-deficient poults. The growth plate zones, with the exception of the mineralized hypertrophied zone, were all increased in length and not modified by treatment. However, the mineralized hypertrophied zones in the 1,25-dihydroxy-vitamin D3 group and the group receiving vitamin D3 in the water were comparable to that in the controls on day 15.5.

Animal Feed↗
PubMedDate not supplied

Experimental rickets in broilers: gross, microscopic, and radiographic lesions. II. Calcium deficiency.

Day-old broiler chicks were fed a calcium-deficient diet for 30 days. Gross, microscopic, and radiographic examinations of the proximal tibiotarsus were done at 2, 3, and 4 weeks of age. In 2-week-old chicks, the growth-plate proliferating-prehypertrophied zone (P-PHZ) was variably lengthened and disorganized, cartilage columns of the degenerating hypertrophied zone and metaphyseal primary spongiosa were shortened, and bone spicules of the secondary spongiosa were bordered by increased osteoid. In 3-week-old chicks, lesions were either similar or more pronounced, with the additional finding of metaphyseal peritrabecular fibrosis. In 4-week-old chicks, the P-PHZ decreased in relative length, osteoid seams and fibrous connective tissue were less prominent, and tibial dyschondroplasia-like lesions were present. Results demonstrated that dietary calcium deficiency produced rachitic lesions, that the lesions were very different from those of phosphorus deficiency or calcium excess, and that the lesions were variable over time.

Aging↗
PubMedDate not supplied

Experimental rickets in broilers: gross, microscopic, and radiographic lesions. III. Vitamin D deficiency.

Day-old broiler chicks were fed a vitamin D-deficient diet for 30 days. Gross, microscopic, and radiographic examinations of the proximal tibiotarsus were done at 2, 3, and 4 weeks of age. In 2-week-old chicks, there was variable lengthening and disorganization of the proliferating-prehypertrophied zone (P-PHZ), resorption of cartilage spicules in the degenerating hypertrophied zone and primary spongiosa, and lengthening of bone spicules in the secondary spongiosa; many bone surfaces were lined with increased osteoid. In 3-week-old chicks, there was a tendency for the P-PHZ to decrease in relative length and for cartilage spicules to increase in length. In 4-week-old chicks, however, there was marked lengthening of the P-PHZ, resorption of cartilage spicules, and replacement of the metaphysis with irregularly oriented islands of woven bone, osteoid, and loose fibrous connective tissue.

Aging↗
PubMedDate not supplied

Experimental rickets in broilers: gross, microscopic, and radiographic lesions. I. Phosphorus deficiency and calcium excess.

Day-old broiler chicks were fed diets high in calcium or low in phosphorus for 30 days. Chicks in both groups had similar gross, microscopic, and radiographic lesions. At 2 weeks, the growth-plate degenerating hypertrophied zone (DHZ) and metaphyseal primary spongiosa were lengthened and decreased in radiopacity. Metaphyseal vessels extended to the growth-plate hypertrophied zone (HZ), and osteoid seams were widened. At 3 and 4 weeks, lesions were similar; however, folding fractures were common and cartilage columns of the metaphysis were thinned and replaced with increased woven bone.

Animals↗